Many evidence-based treatments (EBTs) for common children's mental health disorders have been developed, but they are rarely delivered in real world care. EBTs must be complemented by evidence-based implementation strategies if they are to achieve their promise. Accordingly, the NIH has prioritized efforts to identify, develop, refine, and test implementation strategies (PAR-10-038). Yet, this research is not likely to be fruitful if it is conducted without a thorough understanding of the service systems in which these strategies and EBTs will (hopefully) be deployed. This mixed methods multiple case study will involve seven organizations that are participating in the control arm of an NIMH funded RCT, Testing an Organizational Implementation Strategy in Children's Mental Health (Glisson, PI). This affords the opportunity to examine implementation as usual (i.e., implementation processes that occur in usual care settings) in order to ensure that newly developed implementation strategies will be acceptable, feasible, sustainable, and scalable in the real world. Semi-structured interviews (with agency and clinical directors) and document review will be used to identify and characterize the implementation strategies used in routine children's mental health care (Aim 1), and to explore how organizational leaders make decisions about which EBTs to implement and how to implement them (Aim 2). Focus groups and a project specific self-administered online survey will be used to determine organizational leaders' and clinicians' perceptions regarding the relative importance, acceptability, feasibility, and appropriateness of implementation strategies (Aim 3). Finally, data from the first three aims will be linked to their corresponding organization's scores on a standardized measure of organizational social context (culture and climate) in order to examine how context influences implementation processes and perceptions about specific implementation strategies (Aim 4). By shedding light on implementation as usual, this study will inform efforts to develop and tailor strategies, propelling the field toward the ideal of evidence-based implementation. It will also benefit the RCT by illuminating strategy patterns in the control group, which may aid in the interpretation of results. The proposed research and training plan will allow the fellowship applicant to receive training in: 1) implementation and mental health services research, 2) organizational behavior and change processes, 3) mixed methods research, and 4) scholarly writing and research dissemination. This training will facilitate the successful completion of the proposed project, and will prepare the applicant for an independent research career dedicated to improving the quality of mental health services for children, youth, and families through the advancement of implementation science and practice. The proposed project is consistent with priorities set forth by the NIH and the Institute of Medicine, and is the first step in a larger research agenda to improve the quality of mental health services for children, youth, and families by developing, refining, and testing implementation strategies.